• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). Come here to have fun, be ready to be teased and not take online life too seriously. We now measure and review equipment for free! Click here for details.

RF Interference in Speaker Cables??? (video)

amirm

Founder/Admin
Staff Member
CFO (Chief Fun Officer)
Joined
Feb 13, 2016
Messages
33,023
Likes
111,704
Location
Seattle Area
#1
I don't know how I got dragged into this :) but thought I do a video showing the proper effects of RF on speaker cables and what it takes to demonstrate audibility. I thought it needed to be done even though I did not want to engage in any tit for tat type of videos.

 

cursive

Active Member
Forum Donor
Joined
Feb 13, 2019
Messages
230
Likes
374
#2
Great video Amir. Very educational as always, and great to see you speak on a topic vs just reading the article where some nuances could be lost. "100MHz... we can't hear 100 KHz, how are we gonna hear 100MHz" :D

Again, the regular videos have been such a treat, thanks for taking the time.
 
Joined
Aug 16, 2020
Messages
96
Likes
164
#3
His video consists of him going through websites of snake oil cable companies and reading their marketing fluff, then arrogantly claiming their was a difference because the marketing said so.

Brilliant.

EDIT: Also nice touch calling science that doesn't agree with his snake oil cables... "Flat Earthers?"
 
Last edited:
Joined
Oct 23, 2020
Messages
24
Likes
45
#5
Very well-done video.
Glad I'm not the only one who thought the amplifier feedback noise possibly was a weird argument!
 

alex-z

Active Member
Joined
Feb 19, 2021
Messages
101
Likes
154
Location
Canada
#6
Just when you think Danny cannot ruin his credibility more...

Dude has been shilling tube connectors for years with zero objective data, and is now doubling down with cables. He also engages with anyone who calls out his BS in youtube comments.
 
Joined
Apr 29, 2020
Messages
402
Likes
595
Location
USA
#9
Amir, this video is a very balanced and thorough debunking of the myth that audiophiles need to be worried that RFI has an audible impact on their system. Great explanation of an extremely unlikely edge case where the audio in AM could be demodulated and audible, and that it is not the AM carrier frequency that is heard. I can empathize that addressing someone else's bad arguments is no fun. But having your cool and incisive voice of reason and your hands-on demo enable people with no technical background in this (including me) to understand just how tiny and inaudible RFI in cables really is, is hugely important for audio gear consumers. Now, if you had worn a Japanese fashion hat, this video might make it into YouTube's top 10 popular list of February!

Edit: I also liked the part where you explained how expectation bias can account for a listener's perception of difference in sound between cables, and the importance of blinded tests.
 
Last edited:

tomchr

Addicted to Fun and Learning
Technical Expert
Manufacturer
Forum Donor
Joined
Nov 5, 2018
Messages
654
Likes
1,872
Location
Calgary, Canada
#10
"100MHz... we can't hear 100 KHz, how are we gonna hear 100MHz" :D
We won't hear 100 MHz, but RF can enter audio circuits via cables and get demodulated. It can result in offset shifts in opamps, for example. See fig. 11 in this app note: https://www.ti.com/lit/an/snoa497b/snoa497b.pdf
Don't believe me? Hold a GSM cell phone near an old transistor radio and call the phone. You'll hear a "burr, burr, burr" sound just before the phone rings. You can also toggle airplane mode. As the phone reconnects to the cell network, you'll hear the interference as well. That said, a cell phone transmits at up to 2 W RF power (+33 dBm). Much higher than the -60 dBm Amir measured.

Wifi is a common source of interference as well. The SSID broadcast will create tons of spurs at multiples of 30 Hz that my APx 525 will happily pick up from any circuit sitting on my lab bench. A metal chassis works wonders for keeping that RF out, though.

RF usually enters audio circuits via the input, not the output as the output has much lower impedance. Not thereby said that RF cannot enter through the output of an audio amp. I recall various HAM radio books explaining how to address RF entry with ferrite rods and/or cores.
Modern consumer electronics are supposed to be somewhat RF tolerant (at least if they're marked with the CE or FCC logos). They're also supposed to "play nice" and not emit or conduct RF out of the chassis.

That said, I find it exceptionally unlikely that a different speaker cable would somehow prevent RF entry, though. That part is snake oil.

Tom
 
Last edited:

gags11

Active Member
Forum Donor
Joined
Feb 8, 2019
Messages
145
Likes
251
#11
Reading and watching this, brings back some naive audiophile memories back. I am a scientist and therefore believe in objective data and experiments. But in my early audiophiles days, I remember searching for these unobtanium speaker cables made of silver and who knows what. I actually believed it.

I'm lucky though. One day decided to by a PS audio Perfect DAC to replace my "crappy" Oppo 105. The PS audio arrived, I connected it, and was actually horrified at the sound that this thing produced. I sold it within 2 weeks of owning it. Since then, I decided to evaluate equipment based on actual data, not by cost.
 
Last edited:

GGroch

Addicted to Fun and Learning
Forum Donor
Joined
Apr 7, 2018
Messages
813
Likes
1,465
Location
Denver, Colorado
#12
....Brilliant.....Also nice touch (Danny) calling science that doesn't agree with his snake oil cables... "Flat Earthers?"
I know you are joking, but I find the ASR video series a refreshing change from typical YouTube fare in that Amir does not do that. He seems to go out of his way to be respectful and polite. Of the comments below Danny's Youtube video that referenced ASR, some were over the top mean and spiteful, including a comment by Danny. Amir did not respond in kind. Bravo.

I am forming a hypothesis that in all discussions, there is a direct relationship between how furious, aggrieved, mocking, or belittling a poster is, and the weakness of their argument.
 
Last edited:

wwenze

Addicted to Fun and Learning
Joined
May 22, 2018
Messages
627
Likes
851
#15
We won't hear 100 MHz, but RF can enter audio circuits via cables and get demodulated. It can result in offset shifts in opamps, for example. See fig. 11 in this app note: https://www.ti.com/lit/an/snoa497b/snoa497b.pdf
Don't believe me? Hold a GSM cell phone near an old transistor radio and call the phone. You'll hear a "burr, burr, burr" sound just before the phone rings. You can also toggle airplane mode. As the phone reconnects to the cell network, you'll hear the interference as well.
This was still the case in 2010 when I used those portable headphone amps. These things still exist today, right? I think some websites still do reviews of them. Recently there was this website ran by a pink panther or something...
 

tomchr

Addicted to Fun and Learning
Technical Expert
Manufacturer
Forum Donor
Joined
Nov 5, 2018
Messages
654
Likes
1,872
Location
Calgary, Canada
#16
Edit: I also liked the part where you explained how expectation bias can account for a listener's perception of difference in sound between cables, and the importance of blinded tests.
I bet that accounts for many perceived differences.

I also love the "blind" tests done by groups of friends. "We all heard an effect". Um. Yeah... Look up Asch's studies on conformity from the 1950s. This video is insightful. Also note the update at the end where the neurological consequences of conformity are briefly explained:

Tom
 
Joined
Feb 17, 2019
Messages
8
Likes
13
#17
Years ago, I had an apartment next to a "breaker" with a citizen's band radio set. His conversations could be clearly heard over my stereo. I tried all ways to get rid of this interference, and found that wrapping the speaker cables several times round a ferrite rod placed close to the amplifier greatly attenuated the signal.
CB radios are AM, so the RF signal can be demodulated with a simple rectifier, like a crystal-set, and the non-linearity of the amplifier at 27MHz did this with great efficiency.
I have since had a problem with Taxi base-station transmitters breaking through, but not nearly to the same extent, and have had no problems for over 20 years even with simple, cheap speaker wires even though I live across the road from a different Taxi base-station. I expect that transmitters have improved in the intervening years.
 

tomchr

Addicted to Fun and Learning
Technical Expert
Manufacturer
Forum Donor
Joined
Nov 5, 2018
Messages
654
Likes
1,872
Location
Calgary, Canada
#19
This was still the case in 2010 when I used those portable headphone amps. These things still exist today, right? I think some websites still do reviews of them. Recently there was this website ran by a pink panther or something...
Not quite sure what you're trying to say there.

All I'm saying is that it's not the RF carrier that we hear (DUH!), but that with enough power the RF carrier can still get into circuits and degrade the performance of audio circuits. That's why some of us who manufacture audio gear include EMI/RFI filters on the inputs and in some cases also outputs of said gear.

I happened to work at National Semiconductor when they got the bright idea to include EMI/RFI filters in their opamps. I seem to recall that the LMV851 was the first EMI hardened opamp. I EMI hardened the LMP2021 I was working on at the time as well.
It was the applications engineer on the LMV851 who did the groundwork for the app note I linked to a few posts back.

Tom
 

gags11

Active Member
Forum Donor
Joined
Feb 8, 2019
Messages
145
Likes
251
#20
LOL... I have decided to be fully ignorant about cables. My fingers just navigate to Bluejeans cables website when I need anything (No affiliation whatsoever). Oh... for speaker cables, I usually order the Canare 4s11 locking banana. I hope someone will take this best advice in speaker cable purchase conundrum!

PS: On a serious note, I have found that RF interference and ground loops are more of an equipment problem vs cable.
 
Top Bottom